A database of words such as a synonym dictionary is used to increase precision of supplement of a search keyword, translation, and the like in an information search system, a natural language processing system, a machine translation system, and the like. Various devices for automatically constituting a synonym dictionary are being studied. For example, patent document 1 discloses a semantic dictionary registration device for automatically providing semantic information to an input dictionary entry by using information of a dictionary entry to which semantic information is already provided in a semantic dictionary.